1. Field of the Invention
The present invention relates to a dental chuckless handpiece of the compressed air drive type driven at high speeds, and having an integral structure. Rotary member A which is the most important component of the compressed air drive type dental chuckless handpiece, comprises a shaft having a turbine impeller, a grinding tool fixed to the lower end of the shaft and bearings attached above and below the turbine impeller, which generate and maintain a high-speed rotation even under load, whereby the number of the components involved is reduced to a minimum to achieve reductions in the production cost, and whereby any chuck for the fixation of the cutting tool is dispensed with to achieve improvements in manipulability. The present invention is also concerned with a dental chuckless handpiece of the compressed air drive type, which is of the structure that at least the portions of a handpiece body except its head are formed of a synthetic resin to reduce the weight thereof and discriminably colored with a color including transparent color to afford discriminability thereto.
2. Statement of the Prior Art
In general, because the compressed air drive type dental handpiece driven at high speeds is of the structure that bearings are provided so as to securely and pivotably support a rotary shaft in the head of a handpiece body, it is as a whole formed of brass or stainless steel. This handpiece is also of the structure that, for use, a suitable cutting tool, which dentists or dental technicians wish to employ depending upon the intended purpose or use, is held in a chuck portion formed in a rotary member mounted in the head of a handpiece body.
Thus, because the prior art dental handpiece is of the structure that allows free replacement of cutting tools, the chuck portion is formed in the rotary member mounted in the head of the handpiece body. This leads to an increase in the size of the head, which offers a problem in the observation of the given regions of the teeth or dentures to be ground. Another problem also arises in that the operation of holding the cutting tool stably in the chuck portion is troublesome and difficulty is encountered in maintaining the cutting tool in a stable rotating state free from running-out or co-oscillation. There is also a fear that insufficient chucking may cause disconnection of the cutting tool during cutting, resulting in the patient being injured. Still other problems arise in that the prior art handpiece extremely fatigues the operator who uses it for an extended period, since it is so heavy because of the fact that the whole handpiece is formed of brass or stainless steel, and that noise is generated due to leakage of compressed air out of a hole formed in the head for clamping the chuck.